Model Output Discussion - Into Winter

[Ruzzi]

54 minutes ago, TSNWK said:

06z gfs should give a clue on that.. look at jetstream and heights post vortex plunge end of next week

 

52 minutes ago, northwestsnow said:

Without any Blocking highs at northerly latitudes polar maritime attacks will almost always end with azores heights ridging into Europe via Spain.

The firm favourite is then an ugly NH profile.

Hopefully background drivers save the day later down the line..

In the meantime I'm hoping for a decent cold blast 

This is my point, the basis for most people for this 'mild and wet for the next 3 weeks' narrative is mostly being pushed by model output alone. 

It's far too turbulent to be basing a forecast for the next few weeks off the back of a closer range forecast that hasn't verified yet. 

As stated by someone above, beyond 144 at the moment is up for grabs. There was next to no lead time for the current forecast of the potentially active/ possibly colder with some snow etc spell of weather for next week, to show its hand. Literally the day before it started to materialise people were calling for a very mild Xmas period, not a sniff of colder weather until next year etc. ...... who have conveniently not commented since  

[BartyHater]

Unless you’re a duck, fish or umbrella manufacturer, this is a really grim looking post Xmas jet profile…we really don’t want this to verify, otherwise Dec will go down as another very wet month

Edited December 14, 2023 by BartyHater

[booferking]

2 minutes ago, bluearmy said:

Old news 

Been euro heights returning from the west for quite a while now on the 10/15 day ens 

but watch this space (according to Aaron) and as has been said over and over again - the nwp remains unconvincing 

Hopefully Aaron is on to something my confidence is wobbling slightly.

[frosty ground]

1 minute ago, BartyHater said:

Unless you’re a duck, fish or umbrella manufacturer, this is a really grim looking post Xmas jet profile…we really don’t want this to verify, otherwise Dec will go down as another very wet month

I know just look at those south westerlies 

[Jason M]

1 minute ago, Ruzzi said:

 

This is my point, the basis for most people for this 'mild and wet for the next 3 weeks' narrative is mostly being pushed by model output alone. 

It's far too turbulent to be basing a forecast for the next few weeks off the back of a closer range forecast that hasn't verified yet. 

As stated by someone above, beyond 144 at the moment is up for grabs. There was next to no lead time for the current forecast of the potentially active/ possibly colder with some snow etc spell of weather for next week, to show its hand. Literally the day before it started to materialise people were calling for a very mild Xmas period, not a sniff of colder weather until next year etc. ...... who have conveniently not commented since  

Hmm, not sure that's strictly true regarding the 'sniff of colder weather'. Charts have been showing a NW plunge for sometime between 20th and 25th for several days. The issue is that its going to be a very short and not very potent. Kazim will do well from it sat in the Peak District but most other people won't be impacted much. Xmas could well still be very mild, it just depends on the timing of this 24/36 hour plunge of coldish air. 

Things can change though and we are still 10 / 11 days away. Most charts agree on heights to our south or south west so unless the whole pattern changes its very difficult to see any route to meaningful cold. Only possibility I can see is that the cold plunge turns out as more of a straight northerly. Would still be very short lived though. Just based on years of seeing similar charts I suspect the opposite will happen and the nearer we get the flatter the pattern will be shown.

[CameronWS]

Huge southern bias amongst posts in here this morning I feel. Please at least be neutral and acknowledge the output looks great for some places. This looks a very promising set up for the North West of the country and unusually potent from the direction it’s coming from. Yes it may be short lived but a good chance for many to have some exciting weather.

[BartyHater]

11 minutes ago, frosty ground said:

I know just look at those south westerlies 

Think you must have posted the wrong chart…these are the SW’erlies for the right day.

[weathercold]

17 minutes ago, booferking said:

Hopefully Aaron is on to something my confidence is wobbling slightly.

Not seeing the optimism by Aaron at all, I feel there is a lot of hope casting going on which is understandable but can also be equally misleading for those who hang on to every word.

[Battleground Snow]

Still scope for a violent storm as per the control,

 

[nick sussex]

Coldies having to feed off scraps from the buffet table .

So par for the course for most UK winters .

We haven’t yet plummeted to the buffet table completely empty so it could be worse.

There still seems a lot of faffing about upstream with shortwave energy between model runs .

I think the jury remains out on what to expect in the run up to Christmas . Realistically we aren’t going to see a freeze or widespread snow . 

Marginal conditions for most who aren’t on much higher ground especially further north .

[BLAST FROM THE PAST]

 

Night of The Monster….1st horror film I ever sat through.   That’s one monster and we don’t want that to verify!!

 

BFTP

[booferking]

18 minutes ago, Battleground Snow said:

Still scope for a violent storm as per the control,

 

That would be a red warning

[feb1991blizzard]

3 minutes ago, BLAST FROM THE PAST said:

 

Night of The Monster….1st horror film I ever sat through.   That’s one monster and we don’t want that to verify!!

 

BFTP

i wouldn't mind it verifying but with fully Arctic airmass - so would get a snow bomb.

[Battleground Snow]

Ensembles are trending down as we head towards Xmas day,

[frosty ground]

33 minutes ago, BartyHater said:

Think you must have posted the wrong chart…these are the SW’erlies for the right day.

Your original chart was for the 27th as was mine that’s the 26th, hopefully that clears it up for you

[AdrianHull]

45 minutes ago, CameronWS said:

Huge southern bias amongst posts in here this morning I feel. Please at least be neutral and acknowledge the output looks great for some places. This looks a very promising set up for the North West of the country and unusually potent from the direction it’s coming from. Yes it may be short lived but a good chance for many to have some exciting weather.

I always said this and that the model discussion should be spilt into north ,south especially during these periods. With this current setup I'm expecting a foot of snow in my location over the festive period but Barty Hater is expecting blowtorch south westerlies.

Be good if posters could be a bit more general or use their regional threads more and not just focus on their backyard as this is misleading many members. 

P.s The only reason I use Bartyhaters name is because he is probably one of our most southern members and it's not directed at him

Edited December 14, 2023 by AdrianHull

[BartyHater]

Much better looking 06 GFS Control, which diverges significantly from the Op on Xmas Eve

[MJB]

Control has a festive start to Xmas Day 

Snow for the North 

Kink in the isobars shows the activity moving South 

[Mcconnor8]

1 minute ago, MJB said:

Control has a festive start to Xmas Day 

Snow for the North 

Kink in the isobars shows the activity moving South 

That has snow for basically the entire country during Xmas day 

[booferking]

Let's see those heights grow run by run towards Greenland over Christmas run by run get that first Atlantic low to slide then build on the heights

[damianslaw]

I mentioned yesterday, how short term developments often pop up in unstable airstreams, and we have a very unstable one set to move in during the approach to christmas. Strong temp differentials between cold polar and mild atlantic air is a recipe for both cyclogenesis and therefore secondary lows and runners and ridges that pop up out of nowhere. Consequently calling how things will pan out over christmas in such a set up at this timeframe will always be prone to marked room for error. Will be quite a few days before able to say with some confidence finer day to day details period 22-27 Dec which appears to be the time period many are focused on right now.

[TillyS]

11 minutes ago, Mcconnor8 said:

That has snow for basically the entire country during Xmas day 

Please keep it measured. Snow for the entire country on any day is vanishingly rare, let alone Christmas Day, and the models currently do not give support for such a once-in-a-generation event.

[Mcconnor8]

Just now, TillyS said:

Please keep it measured. Snow for the entire country on any day is vanishingly rare, let alone Christmas Day, and the models currently do not give support for such a once-in-a-generation event.

Was just saying that model run it particular shows that, obviously goes without saying that isn't my expectation.

[Mike Poole]

I am struggling to see the wood for the trees at the moment in the model output, to be honest.

Some kind of cold plunge seems very likely to coincide with the run in to Christmas, but the detail is not discernible, and one reason for that is any snow will depend on being the right side of marginal for many, and the models just can’t tell us that yet.

Beyond Christmas, I have some ideas (which I will post when I have more time) but I feel a little hamstrung because I can’t see a signal in the EPS that remains consistent in the clusters from suite to suite.

I am genuinely interested in a longer cold spell given the current unusual pattern over the hemisphere, the strat, the background signals, but we’re not close enough to it yet to work out exactly how or if it might actually come about.

[johnholmes]

Well some 3 days since I posted the NOAA and ECMWF latest charts, the 6-10 day issue takes us into the Christmas period. I wonder if they suggest a cold one?

NOAA 6-10 out to 23 December and it is showing a very strong westerly into the UK. This from a fairly marked trough off the west coast of north America, into a slight ridging east of this with the westerly over the rest of the chart into the UK. Heights around the Border region are on the lowish side at about 540 DM; (I might be 6DM out as the gradient is so strong making it hard to decipher the actual height). It also suggests, with a large temperature gradient in the east of n America, that there is a good chance of it being a windy and unsettled period in much of the UK. With fairly low heights then wintry type ppn from about the Peak District north on high ground and low ground in the more northern parts of Scotland would be probable. At this distance suggesting anything more detailed is a waste of time. The 8-14 shows 534 DM in the Border area so remaining on the cold side of normal and further disturbed weather likely. That is assuming these two charts are on the correct lines!

Turning to ECMWF, period 20-24 December, and it shows a 500 mb trough just east of the UK, extending SE with a strengthening north of west flow which has backed slightly and also decreased a bit in strength by Xmas Eve. The 850 values are around zero C for much of the country most of the time; the colder air -5C is predicted to be largely well into Europe even in the centre of the extended trough.

Both sets of chart do suggest colder than rather than above normal temperatures. So I’ll be watching how they both develop over the next  3-7 days!

Looking just above my post I see Mike is in about the same place as me!

Climate Prediction Center - 6-10 Day 500mb Outlook

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